The present invention relates to stringed musical instruments, and more particularly to a tremolo apparatus for a stringed musical instrument such as a guitar.
Tremolos are provided on stringed musical instruments for the purpose of changing the tension on all of the strings simultaneously, to thereby change the pitch of the strings. A widely used tremolo apparatus is disclosed in Rose U.S. Pat. No. 4,555,970. In that apparatus, the strings of a guitar are attached to a sustain block which is pivotably mounted so that rotation of the sustain block changes the tension, and therefore the pitch of all of the strings simultaneously. Counteracting the spring force of the strings is a set of two or three tremolo springs which are attached to the sustain block, and to a fixed anchor bracket. A spring urged stop engages the sustain block in a manner such that the spring force of the spring urged stop tends to counteract the force applied by the tremolo springs. This apparatus provides a semi-floating tremolo mode of operation in that the spring-urged stop, in applying a counteracting force to the force of the tremolo springs causes the tremolo apparatus to be more readily used. However, this tremolo apparatus is not convertible to a free-floating tremolo mode without substantial disassembly of it, such as by the complete removal of the springs of the spring-urged stop.
The guitarists familiar with a guitar having a semi-floating tremolo system recognize that it presents a number of advantages, which include the following. The guitar will not go out of tune if one of the strings breaks. Since the strings are not interdependent, tuning of the guitar is easier. The guitarist is enabled to play while resting his hand on the bridge to mute the strings, without causing the guitar to go sharp in pitch. Further, the semi-floating tremolo system allows one string of the guitar to be bent sharp while another is held at a fixed pitch, without the note which is held going flat. This system allows the guitarist to tune one or more of the strings without affecting the tuning of the remaining strings, and also allows the use of a fine tuning mechanism for pitch bending purposes on single strings without affecting the tuning of adjacent strings However, a known disadvantage of the semi-floating tremolo system is that there is created an audible click when the tremolo unit is fluctuated between sharp and flat positions, being created by the sustain block forcibly engaging the stop element. There is precluded, because of this action, the ability of the guitar to produce a voice-like vibrato which fluctuates above and below the standard pitch; does not enable a smooth and consistent tremolo action, and does not have the ability to produce certain unusual sound effects.
It is known, in addition, that the tremolo springs in a tremolo apparatus may be attached to an adjustable anchor: such a construction is shown in Fender U.S. Pat. No. 2,741,146, in which the tremolo springs are connected at one end to the sustain block, and at their other ends to an anchor plate which is of L-shape, with adjusting screws passing through one arm of the L, so that by threading the screws more or less into the body of the guitar, the anchor plate may be moved so as to apply more or less tension to the tremolo springs.